The evaluation of the classical Kirby-Bauer antibiogram method for the determination of antibiotic resistant microorganisms in tap water

Wroclaw University of Science and Technology, Faculty of Environmental Engineering, Wroclaw, Poland

^* Corresponding author: agata.siedlecka@pwr.edu.pl

Abstract

Water supply systems are the main source of potable water for many inhabitants. The European Union and Polish laws demand high quality of tap water, but the aspect of antibiotic resistant bacteria (ARB) is not mentioned. The special emphasis is placed on the presence of pathogenic microorganisms in water, determining by the presence of chosen indicators. Although these regulations provide quite good quality of drinking water, the neglect of resistance vectors could lead to a serious threat to human health. In this study the randomly chosen sample of water from the Wroclaw water supply system was tested in order to evaluate the usefulness of Kirby-Bauer antibiogram method for the assessment of the presence of ARB. The susceptibility testing with 6 chosen antibiotics was performed on bacterial strains isolated from the sample. The diameters of growth inhibition zones were measured and the preliminary identification of strains was carried out, including Gram staining and bacterial cellular morphologies assessments. Although full recognition of the drug resistance phenomenon demands the identification of bacterial species for the comparison with susceptibility testing guidelines, this preliminary research could answer the question, whether the Kirby-Bauer method is sufficient for investigations of ARB dwelling in Wroclaw tap water or the other solution should be applied.